He studied medicine and philosophy at the local university and took part in the fights for the city in 1918 and 1919 as a volunteer on the Polish side.
At the invitation of Jerzy Boczkowski, director of the legendary Qui Pro Quo Theatre, he left for Warsaw in 1924. By 1925 when he moved to Warsaw, he was already a well-known author, working at the Qui Pro Quo cabaret with Julian Tuwim. He was a key figure in the Banda, Morskie Oko, and Cyrulik Warszawski ("Barber of Warsaw") cabarets and author of hundreds of Polish Radio sketches.
He also wrote shmontses (szmonces) (Jewish jokes, monologues and sketches), and jointly composed political sketches with poets Julian Tuwim and Antoni Słonimski.
His unhappy love affair with the Warsaw diseuse Maria Modzelewska inspired many of his songs including Chciałabym, a boję się (Happy Days Are Here Again, aka I"d Love To Do lieutenant, but I"m Afraid)
Soon after the outbreak of World World War II Hemar fled Warsaw after being searched for by the Gestapo and reached Romania, and eventually the Middle East, where he signed up and served in the Polish Independent Carpathian Rifle Brigade. During the war he continued his literary activity, organizing concerts, speeches and field theater plays for Polish troops.
He also organized one of the few theaters operating in besieged Tobruk. He was called "The bard of Lvov, the troubadour of the London emigration".
Foreign 16 years (1953-1969) he prepared and presented weekly cabaret programmes for Radio Free Europe, in which - in prose and verse - he commented upon all the important news from post-war Poland.
After the war, Hemar was unable to return to communist Poland due to the persecution by the Polish authorities of all persons who were politically active. In 1939, he left for Palestine but settled in England in 1941, becoming one of the best-known figures in the Polish diaspora. He continued to be popular in Poland with his weekly program broadcast by the Polish section of the Radio Free Europe.
Hemar died on 11 February 1972 in Dorking, Surrey (near London), and was buried at the local cemetery, although there are plans to move his remains to Poland.
Hemar"s mother was the sister of Stanisław Lem"s father.